Mooring system for a loading station

ABSTRACT

Mooring system for a loading station, i.e. a mooring system for a loading station which can be located in a safe distance from a production platform/vessel, where a conventional tanker with dynamic positioning and bow loading equipment can be connected for loading/unloading from a stationary floating platform/vessel, where a loading station ( 4 ) is connected to a flexible conduit ( 3 ) anchored to the seabed in a point ( 9 ) by at least one line ( 13 ) to at least one anchor ( 5 ) and at least one weight ( 6 ) resting on the seabed.

The present invention relates to a mooring system for a loading station,i.e. a moorings system for a loading station which can be positioned ina safe distance from a production platform/-vessel according the claimpreamble.

Mooring of conventional tankers by Dynamic Positioning (DP) and bow loadequipment for load transfer to/from a fixed or floating platform/vesselis traditionally done via a loading station comprising a hawserconnecting the tanker to the platform. Transfer of load takes placethrough a hose brought from the platform to the bow manifold of theship. The tanker is kept in normal position by means of its DP.

If a change of the direction of wind and/or current takes place, thiscan result in a loading operation being interrupt. An interruptedloading operation can easily entail one or several days delay, of whichcan be very costly for a conveyor, but also for supplier due to tightdelivery conditions. Further, it may also be risky for a vessel tooperate near fixed or floating platforms/ship.

It is therefore an object of the present invention to provide a mooringsystem for a loading station which is positioned in a safe distance froma production platform/ship and which will reduce the risk and the needfor interruption of the loading. This is achieved by the loading systemaccording to the present invention, such as defined by the features ofthe appended claims.

The invention will be described further in connection with an embodimentand with reference to the drawings, in which

FIG. 1 shows the mooring system for the loading station according to theinvention in a standby position before a tanker is connected, and

FIG. 2 shows the same mooring system when the loading station isconnected to a tanker.

Under reference to FIGS. 1 and 2, the system comprises a flexibleconduit 1 or a fixed conduit 2 to the platform/ship. The flexibleconduit 1 will usually be directed through the sea, but can also bedirected on the seabed, whereas the fixed conduit 2 will be directed viathe seabed. The last part of the pipeline will be a flexible conduit 2arranged in a wave configuration. At the end of the wave configurationthe loading station 4 will be provided. From the loading station apick-up-arrangement 11 is fastened and it will be floating on thesurface. The flexible conduit 3 which has a wave configuration, will bemoored in a lower point 9 in the wave configuration by means of oneanchor 5 and at least one weight 6. The entire system, except thepick-up-arrangement 11, is under the surface.

In order to obtain a S-formed wave form for the flexible conduit 3, itis necessary to place some buoyancy elements 10 along some part of theconduit in order to create a positive buoyancy for the entire, flexibleconduit 3. The last part of the S-form will be provided by the loadingstation which has a positive buoyancy.

The loading station 4 comprises a swivel pipe-end-piece 7 as well as abuoyancy element 8 which provide a positive buoyancy for the part of theflexible conduit 3 which are located after the buoyancy element 10, aswell as for the swivel pipe-end-piece 7. At a point 9 on this part ofthe flexible conduit 3, there is by means of at least one line (13)connected an anchor 3 and a weight 6 which will rest on the seabead whenthe loading station 4 is not connected to a tanker. The line 13 cancomprise of a wire, chain and/or a polyester rope. When the system isnot connected to a tanker 12 the weight 6 will compensate for thepositive buoyancy of the buoyancy element 8 and the weight 6 will dropto the bottom and place the loading station 4 at a suitable depth underwater with an pick-up-arrangement 11 floating on the surface. Thepurpose of the at least one anchor is to ensure the loading station 4will be kept at approximately the same position compared to the platformor vessel independent of wind- and/or current direction.

When a tanker 12 arrive to be connected to the system in order to loadto/from the platform/vessel, it will after positioning itself with thebow in correct position to the loading station 4, first pick up thepick-up-arrangement 11 and then pull inn the loading station 4 until theswivel pipe-end-piece 7 can be connected to the bow manifold 12 of thevessel and the loading/unloading can start. When the loading station 4is pulled up, the weight 6 will be lifted from the bottom and “hover”freely until the loading station 4 is lowered into the water after thecompletion of the loading operation.

With such a system the tanker will, if the wind and/or the currentshould change, by means of its dynamic positioning system, rotatesaround the loading station 4 without this creating an immediate risk forthe production platform/-vessel.

1. Mooring system for a loading station, i.e. a mooring system for a loading station which can be located in a safe distance from a production platform/vessel, where a conventional tanker with dynamic positioning and bow loading equipment can be connected for load transfer to/from a fixed floating platform/vessel, wherein the loading station is connected to a flexible conduits anchored to the seabed in a point by at least one line to at least one anchors and at least one weight resting on the seabed.
 2. Mooring system according to claim 1, wherein the loading station comprises a swivel pipe-end-piece and a buoyancy element which provides a positive buoyancy for the loading stations and part of the flexible conduit.
 3. Mooring system according to claim 1, wherein the loading station is kept under the surface by the weight resting on the seabed.
 4. Mooring system according to claim 1, wherein the line consisting consists of a wire, chain and/or polyester rope. 